The objective of the proposed program is to offer basic science training for investigation of growth and development by supporting students in a joint MD/PhD program. This is a continuation of a program, which has been successfully pursued for 37 years. The trainees are selected from students already admitted to the Pritzker School of Medicine. As a minimum, they have a bachelor of science degree and usually two years of medical school training. They are selected on the basis of demonstrated ability in basic science, indication of devotion to pursuit of a research and teaching career in medicine, and outstanding academic credentials. Selection is carried out by a faculty committee and is based on academic records, recommendations, prior accomplishments and personal interviews. All students must fulfill the PhD requirements of a particular basic science department or committee of his/her choosing. The schedule of the training is determined for each student so that basic science courses and research training is integrated between the pre-clinical and clinical phases of medical school. Often certain of the PhD requirements may be completed during elective periods of the pre-clinical curriculum. Completion of research training occurs before or during the final clinical phase of the MD program. Thus the MD/PhD program is usually completed in five or six years, although the training period supported by this grant is often less than five years. Any intermediate funding is provided by the trainee's mentor, private awards or institutional funds. Fifteen to eighteen trainees will be in the program at any given time, allowing admission of three new trainees annually. Based on the past record of this training program, the future trainees will continue to pursue careers in academic medicine and/or research.